Plant-Expressed Receptor Binding Domain of the SARS-CoV-2 Spike Protein Elicits Humoral Immunity in Mice.

Gi Uk Jeong,Byoungshik Shim,Jaewon Lee,Minjeong Song,Youngchan Kwon,Jinyeong Cheon,Sunghwa Choe,Puna Maya Maharjan,Jiyun Jung,Haerim Kim

doi:10.3390/vaccines9090978

Abstract

The current 15-month coronavirus disease-19 (COVID-19) pandemic caused by SARS-CoV-2 has accounted for 3.77 million deaths and enormous worldwide social and economic losses. A high volume of vaccine production is urgently required to eliminate COVID-19. Inexpensive and robust production platforms will improve the distribution of vaccines to resource-limited countries. Plant species offer such platforms, particularly through the production of recombinant proteins to serve as immunogens. To achieve this goal, here we expressed the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein in the glycoengineered-tobacco plant Nicotiana benthamiana to provide a candidate subunit vaccine. This recombinant RBD elicited humoral immunity in mice via induction of highly neutralizing antibodies. These findings provide a strong foundation to further advance the development of plant-expressed RBD antigens for use as an effective, safe, and inexpensive SARS-CoV-2 vaccine. Moreover, our study further highlights the utility of plant species for vaccine development.

Highlights

The recurrent outbreaks of coronavirus (CoV) infections over the last two decades caused by severe acute respiratory syndrome (SARS)-coronavirus-2 (SARS-CoV-2); SARSCoV, 2002, China; and Middle East respiratory syndrome CoV (MERS-CoV), 2012, Saudi
To achieve high yields of receptor binding domain (RBD), an Agrobacterium harboring each RBD expression cassette was infiltrated into the leaves of the glycoengineered-FX N. benthamiana in which the genes encoding plant-specific alpha-(1,3)-fucosyltransferase (F) and beta-(1,2)-xylosyltransferase (X) were knocked out using CRISPR/Cas9 -based genome editing technology
The infiltrated tobacco leaves (4 days postinfiltration (DPI)) developed necrotic phenotypes, which were more severe for T10 and T11 compared with those of T12 and T13 (Figure 1b)

Summary

Introduction

The recurrent outbreaks of coronavirus (CoV) infections over the last two decades caused by severe acute respiratory syndrome (SARS)-coronavirus-2 (SARS-CoV-2); SARSCoV, 2002, China; and Middle East respiratory syndrome CoV (MERS-CoV), 2012, SaudiArabia, have inflicted devastating health and socioeconomic impacts worldwide. The recurrent outbreaks of coronavirus (CoV) infections over the last two decades caused by severe acute respiratory syndrome (SARS)-coronavirus-2 (SARS-CoV-2); SARSCoV, 2002, China; and Middle East respiratory syndrome CoV (MERS-CoV), 2012, Saudi. The sequence of the 30-kb positive-sense single-stranded RNA genome of the novel SARS-CoV-2 is 96%, 80%, and 50%. The SARS-CoV-2 genome comprises 13–15 putative open reading frames that generate 11 proteins, including the structural transmembrane spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins, as well as six accessory proteins [5,6]. Despite high sequence identities among the genomes of these betacoronaviruses, their infection and fatality rates are highly variable, being approximately 2.16%, SARS-CoV-2; 15%, SARS-CoV; and 35%, MERS [1,7,8]. Entry of the virus into its host cell requires the S protein, which involves attachment of S1 to the host cell followed by host–

Methods

Results

Conclusion